1. Field of the Invention
The present invention relates to network interfacing, and more particularly to methods and systems for controlling transmission of data between network stations connected to a European Installation Bus (EIB).
2. Background Art
Local area networks use a network cable or other media to link stations on the network. Each local area network architecture uses a media access control (MAC) enabling network interface cards at each station to share access to the media.
Conventional local area network architectures use a media access controller operating according to half-duplex or full duplex Ethernet (ANSI/IEEE standard 802.3) protocol using a prescribed network medium, such as 10BaseT. Newer operating systems require that a network station be able to detect the presence of the network. In an Ethernet 10BaseT environment, the network is detected by the transmission of a link pulse by the physical layer (PHY) transceiver. The periodic link pulse on the 10BaseT media is detected by a PHY receiver, which determines the presence of another network station transmitting on the network medium based on detection of the periodic link pulses. Hence, a PHY transceiver at station A is able to detect the presence of station B, without the transmission or reception of data packets, by the reception of link pulses on the 10BaseT medium from the PHY transmitter at station B.
Efforts are underway to develop an architecture that enables computers to be linked together using conventional twisted pair telephone lines instead of established local area network media such as 10BaseT. Such an arrangement, referred to herein as a home network environment, provides the advantage that existing telephone wiring in a home may be used to implement a home network environment. However, telephone lines are inherently noisy due to spurious noise caused by electrical devices in the home, for example dimmer switches, transformers of home appliances, etc. In addition, the twisted pair telephone lines suffer from turn-on transients due to on-hook and off-hook and noise pulses from the standard POTS telephones, and electrical systems such as heating and air-conditioning systems, etc.
An additional problem in telephone wiring networks is that the signal condition (i.e., shape) of a transmitted waveform depends largely on the wiring topology. Numerous branch connections in the twisted pair telephone line medium, as well as the different associated lengths of the branch connections, may cause multiple signal reflections on a transmitted network signal. Telephone wiring topology may cause the network signal from one network station to have a peak to peak voltage on the order of 10 to 20 millivolts, whereas network signals from another network station may have a value on the order of one to two volts. Hence, the amplitude and shape of a received pulse may be so distorted that recovery of a transmitted clock or transmit data from the received pulse becomes substantially difficult.
Another transmission scheme is the use of a 2-wire European Installation Bus (EIB) according to EN50090 and DIN VDE 0829 established by the European Installation Bus Association. The EIB system is configured for transmission of 10 kbps data signals, driven by a 24 V DC power supply, between appliances for control of building systems such as lighting and Venetian blind control, heating and air-conditioning control, and management of power outlet interfaces. The EIB bus is configured for connecting up to 64 devices per line via respective bus connectors, each line having various bus structures without a termination resistor.
Numerous problems are encountered if one attempts to supply home PNA network signals in a customer premises having two-wire EIB bus. Capacitive influences on the two wire EIB bus caused by EIB devices and/or end wiring may adversely affect the home PNA signals, limiting the effective transmission distance between two network stations. In addition, high frequency harmonics of the 10 kbps EIB data signals may interfere with the home PNA signals. A substantially large filter would be impractical for implementation within installed bus connectors having a relatively small size in relatively small wall holes having a diameter of about 68 millimeters. In addition, electromagnetic interference caused by the filter elements needs to be avoided.
There is need for an arrangement for interconnecting computer end stations in a network configured for sending EIB signals on a two-wire bus, using a low pass filter having minimal electromagnetic interference and a sufficiently small size for placement within an EIB coupling unit.
There is also a need for separating home PNA signals from EIB harmonic signals for implementation of a network on an EIB bus, using a low pass filter having a small size and minimal electromagnetic interference.
These and other needs are attained by the present invention, where a low pass filter configured for coupling home PNA network signals to a customer premises system having a two-wire European Installation Bus uses an inductor having terminal ends connected to windings and configured in a non-compensating mode for generation of sufficient inductance for low pass filtering of EIB signals from high frequency components of home PNA network signals. Use of an inductor having terminal ends connected to windings in a non-compensating mode enables the use of a smaller inductor core, such as a common mode choke or a ferrite bead toroid, that can fit within an EIB bus connector. Hence, existing EIB bus connectors can be replaced with improved coupling units having low pass filters that enable coupling of home PNA signals to the EIB bus. In addition, use of a toroid having windings in the non-compensating mode creates a closed loop within the toroid for flux induced by the windings, minimizing electromagnetic interference. Finally, use of an improved coupling units having a low pass filter isolates capacitive influences from EIB bus coupling units, ensuring that the home PNA signals are not distorted by the EIB bus coupling units.
One aspect of the present invention provides a method of implementing a local area network in a customer premises having a European Installation Bus (EIB) and two-wire terminals configured for coupling respective EIB bus coupling units to the EIB bus. The method includes connecting to at least one of the two-wire terminals a coupling unit. The coupling unit includes a first two-wire connection, for connecting the corresponding one two-wire terminal to a network node configured for transmitting and receiving local area network signals, and a low pass filter. The low pass filter is configured for passing an EIB signal and rejecting the local area network signal and harmonics of the EIB signal, and includes first and second windings each having first and second terminal ends. The step of connecting the coupling unit includes connecting the first terminal ends of the first and second windings to the first two-wire connection. The step of connecting the coupling unit also includes connecting the second terminal ends of the first and second windings to a corresponding two-wire terminal connector for a corresponding one of the EIB bus coupling units, the windings configured for generating an electromagnetic flux in a same direction induced by any one of the EIB signal and the local area network signals. The connection of the first and second terminal ends of the first and second windings in a configuration for generating an electromagnetic flux in the same direction provides the inductivity needed for the low pass filter using a substantially small inductor device, such as a ferrite bead toroid having a diameter of about 1 cm. Hence, a low pass filter can be implemented for filtering the local area network signal and harmonics of the EIB signal at a sufficiently small size to be implemented within a coupling unit for the EIB bus.
Another aspect of the present invention provides a coupling unit configured for connecting a European Installation Bus (EIB) coupling unit to a two-wire terminal of an EIB bus configured for transmission of an EIB signal. The coupling unit includes a first two-wire connector configured for connecting the two-wire terminal to a two-wire network node terminal, and a low pass filter. The low pass filter is configured for passing the EIB signal between the two-wire terminal and an EIB bus coupling unit two-wire terminal, and rejecting a local area network signal on the two-wire terminal and harmonics of the EIB signal. The low pass filter includes first and second windings each having first and second terminal ends, the first terminal ends of the first and second windings coupled to the first two-wire connector, the second terminal ends of the first and second windings connected to the EIB bus coupling unit two-wire terminal. The first and second windings and the first and second terminal ends are arranged for generating an electromagnetic flux, induced by any one of the EIB signal and the local area network signal, in a same direction.
Still another aspect of the present invention provides a computer network. The computer network includes a two-wire European Installation Bus (EIB) configured for transmission of an EIB signal between EIB bus coupling units connected at respective two-wire terminals, first and second network nodes configured for transmitting and receiving network signals, and coupling units. Each coupling unit is configured for connecting a corresponding network node and EIB bus coupling unit to a corresponding one of the two-wire terminals. Each coupling unit includes a first two-wire connector configured for connecting the corresponding two-wire terminal to the corresponding network node for transmission of the network signals on the EIB bus, and a low pass filter. The low pass filter is configured for passing the EIB signal between the corresponding two-wire terminal and the corresponding EIB bus coupling unit, and rejecting the network signals on the EIB bus and harmonics of the EIB signal. The low pass filter includes first and second windings each having first and second terminal ends, the first terminal ends of the first and second windings coupled to the corresponding two-wire connector, the second terminal ends of the first and second windings connected to the EIB bus coupling unit, the first and second windings and the first and second terminal ends arranged for generating an electromagnetic flux, induced by any one of the EIB signal and the network signals, in a same direction.
Additional advantages and novel features of the invention will be set forth in part in the description which follows and in part will become apparent to those skilled in the art upon examination of the following or may be learned by practice of the invention. The advantages of the present invention may be realized and attained by means of instrumentalities and combinations particularly pointed in the appended claims.